Dear Friends,I'm working on a ducting system with a design temperature 500C and OD 1400mm that is an inlet of equipment with a diameter of 17m and an average temperature of 550-600C. I have designed this line with 2 gimbal expansion joints as attached file. Is it a correct design? Is this system well-arranged for absorbing the radial movement of equipment and absorbing the vertical movement of the duct(22m vertical line)?Do two expansion joints withstand 7m spool between them?Regards,

1. If possible orient horizontal leg perpendicular (appears at 45 Deg to me) to nozzle axis to absorb radial movement from nozzle and vertical expansion.2. I hope you have started with simple EJ such as tied universal etc. prior to using 2 Gimbal EJ's3. For the 7m spool between EJ's, you may provide a spring support.4. What are the restraints in the vicinity of EJ?

Dear Sigma,Thanks for your reply. 1-The equipment is installed in the field and I cannot change the orientation of the nozzle. 2- WIth using tied universal EJ, moments on the expansion joint is about 10 and 9 ton.m in My and Mz. Is it Ok for the Universal EJ? (It should be mentioned that overall lateral movement of expansion joint due to equipment and vertical line movement is 200mm)3- Is it reasonable to report loads on two gimbal expansion joints to the EJs' vendor?4- Spring support with guide support.

If the radial expansion is relatively smaller(<<< vertical), then in present 45deg configuration, I believe the 2-Gimbal EJ arrangement can absorb radial expansion from the equipment, although somewhat less effective than had the horizontal spool oriented 90deg to nozzle axis. Are Caesar-II results any different?

200mm of lateral movement would result in ~1.64 Deg of rotation for each bellow (with 7m pipe spool in between) and should not be an issue to EJ vendor. Please show restraints local to EJ in the datasheet (a small sketch for better understanding), so that the EJ vendor can review the adequacy of supports.

And yes, those external piping loads (over and above the pressure thrust loads) should be sent to EJ vendor for proper design of external hardware.

The radial expansion of equipment is about 90mm, and this movement causing the lateral movement in two gimbal expansion joints assembly and pushing them along the horizontal line.Another question: Is a 3 gimbal expansion joints route a stable system? please see attached file. Two gimbal expansion joints are in a leg that has an angle in x-y and z-y direction. Line temp= 500C, The right equipment movements: vertical movement=230, x and z direction: 50~60mmEJ No. 1= Simple(fabric), No.2,3,4 =GimbalI think another solution for this route is using tied universal EJ with 2 rods(for having the lateral and angular movement in this EJ)instead of EJ No.4. I would greatly appreciate it if you kindly give me some advice.

However, you have to have a system that's protected from the effects of gravity causing the segments between joints from slumping over.

In the diagram on the site, you should assume that the pipe is in the horizontal, and that the hole thing is universally supported, and that the make-up the ball joints perform is exclusively in the horizontal plane.

Sigma,Nozzle allowable load of adjacent equipment is low and I cannot use the metallic expansion joint. Movement of the nozzle in left side equipment is about 30,40 mm in the vertical and radial direction, thus movement*stiffness of metallic expansion joint is higher than allowable load. What is the problem with the fabric expansion joint at temp 500?Michael,I think it is better to change EJ4 to Hinged type for the stability of the system. Also, the orientation of hinged should be in accordance with the picture. But the orientation of EJs are about 3-4 degrees and the use of spring support(spring can for under pipe) may be impossible, and I should use hanger. Do you have any advice on the design of the line?

All three proposals have one common problem. Not enough space for the ancillaries. In some cases can be solved by high expense. 500 C is quite high temperature and normally floating ring designs are required.

As a general comment. Most pipe designers give insufficient space for the expansion joints. Add to that unnecessarily low spring rates, wrong movements... Pipe designers should realize that bellows element goes often well past the yield point and it has impact on force directions.

One of the biggest mistakes with the movement specification is to give equal movement in two directions. Lets assume the 500 C case. CAESAR II gives compression 50 mm and the stress engineer specifies 50/-50 mm movement for the expansion joint. Big mistake. 50 mm compression is a result of 480 C temperature difference. To have 50 mm expansion the pipe temperature should go to about -460 C. Expansion joint can be designed for these movements but it is less safe compared to the one where movements are specified correctly.

Just to remind again: Expansion joint with tie rods cannot have axial movement.

I have designed expansion joints well over 20 years, try to train engineers and have special design software and I battle with these issues every day - world wide.